Method of punching a cylindrical crt convergence electrode



E. E. YORNS Nov. 18, 1969 METHOD OF PUNCHING A GYLINDRICAL cm CONVERGENCE ELECTRODE Original Filed Oct. 18, 1966 FIG! 74! Ill FIGS FIGA

INVENTOR EDWARD E.YORNS ATTORNEY United States Patent "ice 3,478,628 METHOD OF PUNCHING A CYLINDRICAL CRT CONVERGENCE ELECTRODE Edward E. Yorns, Owensboro, Ky., assignor to Kentucky Electronics, Inc., Owensboro, Ky., a corporation of Delaware Original application Oct. 18, 1966, Ser. No. 587,519, now Patent No. 3,354,338, dated Nov. 21, 1967. Divided and this application Sept. 14, 1967, Ser. No. 667,707

Int. Cl. B2611 3/12; B'23d 21/00 US. CI. 8354 2 Claims ABSTRACT OF THE DISCLOSURE This is a division of Ser. No. 587,519 for Convergence Electrode Structure, filed Oct. 18, 1966, now Patent No. 3,354,338.

This invention relates to method of punching cylindrical cathode ray tube convergence electrodes with parallel slits for receiving magnetic convergence pole pieces.

In color television cathode ray tubes with three electron guns the terminal gun electrode is generally a convergence electrode which separates the three beam paths and provides a set of magnetic pole pieces for each beam to produce converging influence on the beam by electromagnetic structure mounted outside the tube envelope.

These convergence electrodes thereby are generally cen-' tered within the glass neck of the cathode ray tube by fingers or snubbers extending from the electrodes to frictionally engage the inside circumference of the tube neck with spring pressure.

Conventionally, these convergence electrodes have been made from a cylindrical cup-shaped non-magnetic member which has three sets of spaced long linear slots punched through the cylindrical walls of the cup for receiving in registration therethrough generally L-shaped magnetic pole pieces on either side of each separate beam passing through a corresponding hole in the bottom of the cup. These pole pieces are then welded into place on the outer cup surface and a snubber finger is held in position by a jig assembly in the center of the two pole pieces and is welded to the outside surface of the electrode.

This conventional construction, however, has been found unsatisfactory in accordance with this invention. One of the defects is the difiiculty of maintaining tolerances on the tooling for punching the linear slots through the cylindrical walls. It has been found that the punches strike the outer surface of the cylindrical cup on a nonradial path so that the cylindrical surface of the cup tends to deflect the punches or spread the punches apart if used in pairs.

It is an object of this invention to provide improved methods of punching slots in convergence electrodes for receiving pole pieces.

A more general object of the invention is to provide improved methods of punching elongated slits in the Walls of cylindrical tubes.

Thus, in accordance with one aspect of the invention, a cylindrical convergence electrode has punched therein 3,478,628 Patented Nov. 18, 1969 and spaced over a small segment of the cylinder surface a pair of elongated slots which have at least one generally normally extending transverse slot structure comp-onent, to thereby permit a punch shaped with a significant lateral dimension away from the elongated slot in at least one position along its length. Thus, an L-shaped or U-shaped punch structure may be used to prevent the changes in tolerance caused by spreading or deflection of the punches in the construction of prior art convergence electrode slots.

Detailed aspects of the invention, its nature and construction together with further features and objectives are set forth in the following specification and the accompanying drawings, wherein:

FIGURE 1 is a perspective sketch of a convergence electrode structure embodying the invention;

FIGURE 2 is a plan view in section of the convergence electrode structure taken along lines 2-2 of FIGURE 1;

FIGURE 3 is an enlarged elevation view, partly in section, of a convergence electrode provided in accordance with the teachings of this invention;

FIGURE 4 is a broken away perspective view of a typical punch configuration used in accordance with the teachings of this invention, and

FIGURE 5 is a broken away view, partly in section, of a convergence electrode and associated punches for pole piece slits.

The convergence electrode 10 of FIGURES 1 and 2 is fashioned to show the departures from conventional construction afforded by this invention in phantom lines. Thus, the convergence electrode 10' is a cup-shape electrode as found in the terminal electrode of a three beam color television cathode-"ray tube. In the bottom of the non-magnetic cup structure are three apertures 11 through which the respective beams pass as they traverse axially through the cylinder between respective pairs 14, 15 of magnetic convergence poles extending through a pair of elongated parallel slots 16, 17 punched through the cylinder walls over a small segment of less than of the cylindrical cup surface to extend longitudinally generally in a path parallel to the path of the corresponding beam through the cylinder. It may be seen that the generally planar L-shaped magnetic pole pieces 14, 15 do not extend radially into the cylinder, but bracket the path of the beam through the apertures 11. Thus, an elongated blade-like planar punch placing apertures 16, 17 through the walls of the cylinder tends to be deflected out of tolerance and worn by the action of the cylindrical surface.

Accordingly, this invention provides for the shaping slots 16 and 17 to have at least one generally transversely extending slot structural component 20 so that the punch 21 can be shaped as shown in FIGURE 4 in L-shape or U-shape which avoids the deflection and wear problem. Other punch shapes as noted by phantom filet 22 may be utilized without departing from the spirit of this invention.

As seen from FIGURE 5, punches 21A and 21B are disposed on opposite sides of the plane 50 passing through the axis 51 of the cylindrical electrode 10', and are adapted to be moved generally parallel to this plane 50 by means of some movable mechanism 52. The punches 21 can be singly or simultaneously used, but preferably are moved simultaneously in pairs, as shown.

It is generally evident from the spacing of the slits that the punches strike the cylinder walls within a sector defined by acute angle 0: extended from the axis 51 of the cylinder. Accordingly, the elf-normal engagement of the punches produce the problems herein-before described.

It is evident from the foregoing specification that a significant problem of punch wear and punching tolerances has been solved by this invention and the novel methods of punching slits in convergence electrodes as defined by the appended claims in particularity set forth the spirit and nature of the invention.

What is claimed is:

1. The method of punching at least one pair of generally longitudinal and parallel slits side by side in the circumference of a thin metal Wall of a cylindrical con vergence electrode of a cathode ray tube, or similar workpiece, With the slits lying within a sector defined by an acute angle extended from the axis of the cylinder, comprising the steps of selecting a pair of punches for forming apertures comprising said slits With such shape that there is at least one generally normally extended transverse aperture component along the length of the slit wherein the punches have their transversely disposed cutting member integrally disposed with the slit cutting member,

disposing the punches on opposite sides of a plane passed through the axis of said cylindrical electrode so oriented that the slits are parallel with the cylindrical axis and the transverse punch member is substantially normal to the punch axis, and

moving said punches into and through the Walls of said cylinder along the direction of movement generally parallel to said plane to strike the cylindrical surface of said electrode on either side of said plane and oif normal to said cylindrical surface thereby punching into said cylinder said parallel slits With a transverse aperture portion extending away from the axial body of the slit.

2. The method defined in claim 1, including the step 10 of movingsaid pair of punches simultaneously into the Walls of the cylinder on opposite sides of said plane.

877,855 1/1908 Murray 83--192 X FRANK T. YOS T, Primary Examiner US. Cl. X.R. 

